Preliminary Genomic Analysis of the RSV Surge 2022 in Massachusetts Reveals a Polyphyletic Epidemic Driven by the Expansion of Multiple Lineages | Virus World | Scoop.it
From virological.org - December 10, 2022 11:37 AM

Introduction

 

As reported by the United States (US) Center for Disease Prevention and Control, the US experienced an early and severe respiratory syncytial virus (RSV) surge in autumn 2022. This increase in RSV cases relative to previous years, alongside coincident epidemics of SARS-CoV-2 and Influenza, has put intense pressure on hospitals and urgent care centers [1]; however, the factors promoting the surge in cases are unknown. A leading hypothesis suggests an increase in the susceptible population brought on by limited RSV circulation during COVID-19, particularly involving children ages one to three, who are among the most susceptible to severe RSV [2]. Alternatively, the emergence of a highly transmissible and/or virulent “variant” of RSV could account for the increase. These possibilities can be distinguished by genome sequencing of surge-associated samples because a highly-transmissible variant will appear as a cluster of closely-related sequences in a phylogenetic tree. To characterize the viral genomic basis of the 2022 RSV surge in Massachusetts (MA), we sequenced RSV genomes and analyzed clinical data from symptomatic patients who presented to the Massachusetts General Hospital (MGH), a large academic medical center in Boston, MA, and its affiliated outpatient practices in the Greater Boston Area.

 

Discussion

 

We show that the expansion of multiple clades has contributed to the RSV surge in MA in the autumn of 2022. In cases sampled during the peak of the surge at a major academic medical center and its affiliated outpatient practices in the greater Boston area, RSV-A predominates, and circulating clades have a MRCA more than 5 years before the present. The polyphyletic nature of viral genomes sequenced in eastern MA suggests that the emergence of a single, highly transmissible RSV lineage is unlikely to account for the 2022 surge. Additional genomic and immunological data are needed to fully understand the causes of the 2022 RSV surge, including pre-COVID-19 pandemic sequences to evaluate changes in RSV genomic diversity during the COVID-19 pandemic.

 

Published in Virological.org (Dec. 9 , 2022)